Immunohistochemical Localization of Acetaminophen-Bound Liver Proteins

A sensitive immunofluorescence assay was developed for localizingacetaminophen (APAP) protein adducts in liver sections fromtreated mice. Affinity-purified anti-APAP antibodies, when appliedto liver sections from mice given 600 mg APAP/kg, po, were preferentiallylocalized in cells of the centrilobular region. At 30 min afterdosing, covalently bound APAP was detected only in those cellsmost proximal to the central vein. Thereafter, binding spreadthroughout the centrilobular zone. However, by 8 hr the overallintensity of staining decreased and binding appeared more diffuse.Western blot analysis of electrophoretically resolved proteinsfrom similarly treated mice revealed a corresponding temporalarylation of cytosolic proteins by APAP and indicated that thefluorescence detected at 30 min was associated with arylationof protein(s) of 44 kDa. The findings demonstrate the sensitivityand utility of immunohistochemical techniques in the study ofcovalently bound toxicants and emphasizes the temporal linkbetween selective protein arylation in individually targettedcells to the development of APAP hepatotoxicity.